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Materials you will need to make a bulb

One small jar
Cork stopper for a lid
A 1-inch nail
Three feet of shielded copper wire
One 6-volt battery--not a car battery!
Thin iron wire (the best source for this is unraveled picture hanging wire)

Materials you will need to record your results

A copy of the "Record my results" form
A watch with a seconds hand
A pencil

This experiment needs to be done with an adult present and supervising it! (2) Always wear safety glasses and gloves when doing experiments! (3) Be careful handling the filaments when they burn out--they will be HOT! (4) Never play with wall sockets or household electric currents.


Print your "Record my results" form. You will need it to record the results of your experiment.
First cut the copper wire into two lengths about 1-1/2 feet long. Cut off an inch of the shielding (plastic coating) at each end of the strands.
With a nail, drill two holes into the cork.  Push the wire through the holes in the cork so that about two inches of the wire can be seen in the jar.
Make a hook at the end of the copper wires so that you can twist small strands of iron wire around them to make a filament.
Twist several strands of iron wire together and stretch them across the gap between the two copper hooks to form the filament.
Put cork stopper with filament inside the jar.

Carefully hook up both copper wire ends to the battery and watch your bulb light up! 

Be careful the filament becomes very hot. Do not touch.

Use the watch to time how long your filament glows. Keep a record of how long your filament lasts on the "Record my results" form.
Try the experiment again with a different number of iron wire strands twisted together. Record your results.

The Lemelson Center for the Study of Invention and Innovation
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